Aromatization process

ABSTRACT

Paraffinic hydrocarbons having at least 6 carbon atoms are aromatized at low pressures, preferably atmospheric pressure, in the presence of a novel catalyst comprising a bivalent metal, tetravalent molybdenum and oxygen in chemically combined form supported on deacidified alumina. The supported form comprises a compound having the formula M2Mo3O8 where M is a bivalent metal having an ionic radius not greater than 0.95 A.

ir States Patent [191 Tauster et al.

[ 1 Mar. 18, 1975 1 AROMATIZATION PROCESS [76] Inventors: Samuel J.Tauster, l0 Galahad Dr.,

Englishtown; John H. Sinfelt, 296 Chaucer Dr., Berkley Heights, both ofNJ.

22 Filed: May 15, 1973 21 Appl. No.: 360,441

Related US. Application Data [60] Division of Ser. No. 79,665, Oct. 9,1970, Pat. No. 3,769,238, which isa continuation-in-part of Ser. No.724,589, April 26, 1968, abandoned.

2,692,846 10/1954 Oblad ct a], 260/6735 2,710,826 6/1955 Weikart2,873,248 2/1959 Tate et a1 2,943,067 6/1960 Sieg 260/6833 2,967,8221/1961 Moy et al 208/136 FOREIGN PATENTS OR APPLICATIONS 747,969 12/1966Canada 260/6735 Primary ExaminerDelbert E. Gantz AssistantE.taminerJames W. Hellwege Attorney, Agent, or FirmL. A. Proctor [57]ABSTRACT Paraffinic hydrocarbons having at least 6 carbon atoms arearomatized at low pressures, preferably atmospheric pressure, in thepresence of a novel catalyst comprising a bivalent metal, tetravalentmolybdenum and oxygen in chemically combined form supported ondeacidified alumina. The supported form comprises a compound having theformula M Mo,,O where M is a bivalent metal having an ionic radius notgreater than 0.95 A.

f 11 Claims, NoDrawings AROMATIZATION PROCESS This is a division of US.application Ser. No. 79,665, filed Oct. 9, 1970, now US. Pat. No.3,769,238, which is a continuation-in-part of US. application Ser. No.724,589, filed Apr. 26, 1968, each entitled Aromatization Catalyst andProcess, now abandoned.

This invention relates to hydrocarbon conversion processes and toimproved catalysts therefor. More particularly, this invention relatesto processes for aromatization of paraffms and to novel catalystscomprising a compound of a divalent metal, molybdenum and oxygen,designated as ternary molybdenum (1V) oxide, supported on deacidifiedalumina.

Catalytic reforming is widely used commercially in order to improve theoctane rating of feedstocks boiling within the motor fuel range.Basically, the opera tion involves the contacting of a naphtha, eithervirgin, cracked, Fischer-Tropsch or mixtures thereof, with a solidcatalytic material at elevated temperatures and pressures in thepresence of recycled hydrogen, usually using a plurality of reactors inseries. Platinum, which is regenerable, is the most widely usedcatalyst, and the process is generally conducted in a fixed catalystbed. Both semi-regenerative and cyclic processes are used.

Several reactions take place in the platinum reforming process. Theseinclude: (1) dehydrogenation of naphthenes to the corresponding aromatichydrocarbons, e.g., dehydrogenation of cyclohexane to benzene; (2)isomerization and dehydrogenation of alkylcyclopentanes such asmethylcyclopentane to form benzene; (3) aromatization of straight chainparaffins to form aromatic compounds, e.g., conversion of n-hexane andh-heptane to benzene and toluene, respectively; (4) isomerization ofstraight chain paraffins to form branched chain paraffins; and (5)hydrocracking of the higher boiling constituents of the feed to formlower boiling constituents.

Platinum reforming gives excellent conversion of naphthenes to aromaticswith high selectivity, with an attendant substantial increase in theoctane number of the effluent over the octane number of the feed.However, paraffins are converted to a much lesser extent, and theselectivity of paraffin conversion to aromatics is low. Instead, asubstantial portion of the paraffin content of the feed is convertedinto C -C hydrocarbons. The research octane number (RON) of the effluentis dependent on the severity of reforming. Under relatively mildconditions, a relatively small percentage of the paraffin content isconverted, but the octane number of the effluent is relatively low, forexample, about 85 to 90. Higher octane number effluents can be obtainedusing more severe reforming conditions. Under these conditions asubstantial portion of the paraffinic content is converted, but much ofthis conversion is to light hydrocarbons, i.e., C,C rather than to themore desirable aromatics which raise the octane number of the product.

Further drawbacks of platinum catalysts are their scarcity and highcost. Because of these drawbacks, togethcr with the increasing demandsfor high octane motor fuels, it is imperative to find alternativecatalysts.

Among the characteristics which an aromatization catalyst should possessare: high conversion, high selectivity for the production of aromatichydrocarbons with a minimum of side reactions, high activity over a longperiod of time, and ease of regeneration with substantially completerestoration of catalytic activity. Al-

though various catalysts other than platinum and the platinum metals andtheir compounds have been reported in the literature, none havepossessed all of these characteristics to a sufficient degree to achieveany substantial commercial usage in the production of aromatics. One ofthe best of the non-precious metal catalysts known heretofore is achromia-alumina type catalyst described in Canadian Pat. No. 747,969,issued Dec. 6, 1966. The catalyst described in this patent compriseschromium oxide on a support of alumina which has been deacidified bydoping with a small quantity of a cesium compound sufficient tointroduce about I to 5 gram atoms of cesium per I00 gram moles of A1 0This catalyst has high initial activity for the aromatization ofhydrocarbons such as n-hexane and n-heptane. However, conversion dropsrapidly in a comparatively short time on stream, with some loss ofselectivity accompanying the drop in conversion. Furthermore, catalyticactivity is not fully restored on regeneration.

lt is an object of this invention to provide a new aromatizationcatalyst which is characterized, in a process for aromatization ofhydrocarbons, by high conversion, high selectivity, good catalyst life,and good regenerability.

A further object of this invention is to provide an improved process forthe aromatization of hydrocarbons using the novel catalyst of thisinvention.

The new catalysts of this invention comprise a catalytically-activematerial, designated as a ternary molybdenum (lV) oxide, comprising adivalent metal, tetravalent molybdenum, and oxygen in chemicallycombined form, and a support comprising deacidified alumina. Thecatalytically active material is a compound having the formula where Mis a divalent metal having an ionic radius not exceeding 0.95 A(Periodic Table of the Elements; E. H. Sargent & Co.; copyright 1962).These catalysts are formed by impregnating the support successively withwater-soluble salts of hexavalent molybdenum and of the deisred divalentmetal, calcining, and reducing the molybdenum from the hexavalent to thetetravalent state. This catalyst is useful in carrying out variouschemical reactions and particularly for aromatizing paraffms, especiallystraight chain paraffins.

Paraffinic hydrocarbons containing at least 6 carbon atoms arearomatized according to the present invention by contacting a feedstockcontaining the hydrocarbon with the above-described catalyst. Thisreaction is carried out at low pressure, i.e., about 0.5 to 5atmospheres and preferably at atmospheric pressure, and at a temperatureof about 850F. to about 1,050F., preferably about 900F. to about 1,000F.The space velocity is generally in the range of about 0.1 to 4 V/V/Hr.High conversions of paraffmic hydrocarbons, with high selectivity ofaromatics formation, are obtained.

The feedstock for aromatizations according to this invention comprisesparaffmic hydrocarbons having at least 6 carbon atoms, and particularlyn-hexane and nheptane. The feedstock may be the effluent from a platinumcatalyst reformer or a cut from the pipestill containing appreciablequantities of n-hexane and C paraffins. Substantially pure n-hexane andn-heptane can also be treated. The feedstock is contacted with thecatalyst, either in a fixed or a moving bed.

The catalyst, as indicated earier, comprises (a) a catalytically-activematerial containing a divalent metal, tetravalent molybdenum, and oxygenin chemically combined form, and (b) a support comprising deacidifiedalumina. The divalent metal is one having an ionic radius not exceedingabout 0.95 A in the divalent state.

Molybdenum in the catalytically-active materials of the presentinvention has an oxidation state of +4. Molybdenum having an oxidationstate of +4 will be referred to herein as tetravalent molybdenum," andthe catalyst is designated as a ternary molybdenum (1V) oxide. Thecatalytically-active material is a compound having the formula where Mis a divalent metal. Preferred divalent metals represented by M aremagnesium, zinc, iron, cobalt, and nickel as previously indicated.Compounds of the above formula are known per se, having been described,for example, in W. H. McCarroll et al., J. Am. Chem. 500., 79, 5410-5414(1957), and in C. B. Ansell et al., Acta. Cryst., 21, 482 (1966), butthe compounds have never been formed as an active part of a catalyticcomposite, nor have their utility as catalysts ever been heretoforeappreciated.

The support for the present catalysts is deacidified alumina, i.e.,alumina containing a small amount of a Group IA or "A metal oxide asdeacidifying agent. Exemplary of such deacidifying agents are salts suchas halides, nitrates, carbonates or the like of the Group 1A or 11Ametals which will decompose to form a basic oxide in situ, e.g., theoxides of lithium, sodium, potassium, beryllium, magnesium, and thelike, though various other oxides and salts can be employed to effectdeacidification of the acid sites on the support as will be apparent tothose skilled in the art (see, e.g., U.S. Pat. No. 3,692,293). Theamount of deacidifying agent is generally equivalent to about 1 to gramatoms of the Group IA metal per 100 moles of alumina. Small amounts ofsilica may be present in the support, although such presence ordinarilyis not preferred.

The preferred carrier or support for catalysts of this invention iscesium-doped alumina such as that described in Canadian Pat. No.747,969. Some aromatization activity is obtained by impregnatingconventional catalyst carriers, such as silica, alumina, or mixtures ofthe two, with the catalytic compound of this invention, butaromatization selectivity is usually considerable worse when anacid-type carrier such as unmodified alumina or silica-alumina is used.In order to obtain good selectivity, the carrier is deacidified,preferably by doping with a small percentage of cesium as described inthe aforementioned Canadian Pat. No. 747,969. Doping is effected byimpregnating the alumina support with a water-soluble cesium compound,and by calcining the alumina so that the cesium atoms diffuse into andbecome part of the alumina crystal lattice. Various adsorptive aluminassuch as gammaalumina, eta-alumina, and hydrated aluminas such asalpha-alumina monohydrate, betaalumina trihydrate, and mixtures thereof,may be used, and excellent results have been obtained using beta-aluminatrihydrate. The amount of cesium introduced into the alumina correspondsto about 1 to 5 gram atoms Cs per 100 moles of A1 0 Excellent catalystsupports for this invention have been obtained using 5 moles of Cs, asCs O, per 100 moles of A1 0 The catalyst of the present inventioncontains a major proportion of deacidified alumina support and a minorproportion of catalytically-active agent. The composition of thecatalyst, stated in gram atoms of metal per 100 moles of alumina, is asfollows: divalent metal M, l to 60 gram atoms; M0, 1.5 to gram atoms; Cs(or other Group IA metal), 1 to 5 gram atoms. (All metals are present inchemically combined form and M0 is in the tetravalent state, aspreviously emphasized.) It will be observed that the ratio of divalentmetal M to molybdenum is not necessarily 2:3, which is thestoichiometric ratio corresponding to the formula M Mo O There may be anexcess of Metal M. In that case, it is theorized that the excess ispresent as the metal oxide MO. Molybdenum may also be present in excess,in which case any excess is probably present as the oxide M00 Generally,the divalent metal M will be present either in the stoichiometricquantity corresponding to the formula M Mo O or in excess. In apreferred embodiment, a catalyst is obtained in which the molar ratio ofconstituents, stated as gram atoms of metal per moles of A1 0 is asfollows: MzMozC- s:Al O 2030:3045:35:100.

The catalyst of this invention may be prepared by impregnating thecesium-doped alumina support successively with a water-soluble compoundof molybdenum and a water-soluble compound of the divalent metal,calcining after each impregnation, followed by treatment with hydrogento reduce the molybdenum from the +6 to the +4 oxidation state. Theorder of impregnation of molybdenum and the divalent metal is notcritical, but for the purposes of illustration the present inventionwill be described with reference to a procedure in which the support isimpregnated first with molybdenum. In accordance with such a procedure,the support, preferably cesium-doped alumina, is impregnated with awater-soluble molybdenum salt such as ammonium heptamolybdate, (NH Mo O,-4H O, the impregnated support is dried and then calcined at elevatedtemperature in the range of about 800F. to about 1,100F. This yieldsmolybdenum trioxide supported on cesium-doped alumina. The concentrationof the impregnating solution is chosen so as to introduce the desiredquantity of M00 The supported molybdenum trioxide on alumina thusobtained is then impregnated with a water-soluble salt of the desireddivalent metal. Nitrates are particularly well adapted for thisimpregnation; for example, magnesium nitrate, cobalt nitrate, and nickelnitrate may be used. Of course, other water-soluble salts of thesemetals, such as the chlorides, may also be used. The concentration ofthe solution may be chosen so as to introduce the stoichiometricquantity of divalent metal corresponding to the formula or an excess ofthe divalent metal (a deficiency of divalent metal M may be introduced,but this is not the usual procedure). Excellent results have beenobtained, for example, by impregnating the salt with equimolarquantities of metal oxide, MO, and molybdenum trioxide, M00 The desiredcompound M Mo O is formed, even though the divalent metal is present inexcess.

After the catalyst support has been impregnated with both molybdenum anddivalent metal, and before the catalyst is put into use, the molybdenumis reduced from the hexavalent to the tetravalent state. This is readilyaccomplished in most instances by passing hydrogen through a bed of thesupported catalyst at elevated temperatures, e.g., about 1,000F. to1,300F., and at atmospheric or elevated pressure, for example, about 0to 400 psig. After all of the molybdenum has been reduced, the catalystis then ready for use.

Aromatization according to the present invention is carried out at lowpressures and at elevated temperatures, and in the absence of any addedhydrogen in the feed. The aromatization may be carried out quite well atatmospheric pressure, although generally pressures in the range of about0 to about 60 psig are suitable. Preferred operating temperatures areabout 900F. to 957F., although temperatures of about 850F. to 1,050F.may be used. The space velocity of hydrocarbon feed, expressed involumes of hydrocarbon (measured in the liquid state) per unit volume ofcatalyst per hour (V/V/Hr.) may range widely, for example, from about0.1 to 4.0, and typical space velocities are in the range of about 0.3to about 1.0 V/V/Hr. It is known that addition of hydrogen with the feedis detrimental to the formation of aromatics, and therefore the use of apure hydrocarbon feed (i.e., no added hydrogen) is preferred.

The present invention gives outstandingly good results in the conversionof hydrocarbons, such as nhexane and n-heptane, to aromatics. Forexample, initial conversions of 60% or higher with selectivities of 90%or more may be obtained with the catalyst of this invention. Selectivityis defined as the quantity of aromatic hydrocarbon formed, divided bythe amount of aliphatic hydrocarbon which is reacted. A particularlydesirable feature of the catalysts of this invention is that selectivitydoes not diminish appreciably, even when the catalyst has been on streamfor a substantial length of time. In this respect the catalyst of thisinvention compares most favorably with the chromia on cesiumdopedalumina catalyst (where the cesium-doped alumina is identical to thatused herein) described in Canadian Pat. No. 747,969. While the initialconversions and selectivities may be slightly higher using the chromiaon cesium-doped alumina catalyst of the Canadian patent, there is anappreciable decline in both conversion and selectivity using the chromiacatalyst, while there is very little loss of selectivity (althoughthere, is some loss of conversion) using the supported ternarymolybdenum (IV) oxide catalysts of this invention.

A further outstanding feature of the catalysts of this invention is thatthey may be regenerated easily with substantially complete restorationof catalytic activity. Regeneration may be accomplished with either airof hydrogen. One regeneration procedure is to regenerate with hydrogenat an elevated temperature, e.g., about 850F. to l,300F. Regenerationwith hydrogen is more easily carried out than with air and is thereforepreferred. The catalysts of this invention are unusual amongaromatization catalysts in that most catalysts of this class must beregenerated with air or oxygen and cannot be regenerated effectivelywith hydrogen.

The present invention can also be used for the upgrading of naphthafeedstocks containing appreciable portions of paraffmic hydrocarbons andboiling in the motor fuel range. For example, a conventional reformatefrom a refinery may be contacted with the catalyst of the presentinvention at low pressure, e.g., atmospheric pressure, and at low spacevelocities in the range of about 0.1 to 4 V/V/Hr. In such an operation,the hydrocarbon feedstock may be first catalytically reformed, as forexample with a platinum catalyst, and at elevated tempertures andpressures according to procedures known in the art. The effluent fromthe last reactor is cooled and passed to a separator drum where thecondensed reformate is separated from the uncondensed tail gas. Aportion of the tail gas which is rich in hydrogen is recycled; theremainder is treated according to known procedures to recover C andheavier hydrocarbons, The hydrocarbon reformate is then further refinedand upgraded according to this invention. This reformate, which consistsprimarily of hydrocarbons boiling in the motor fuel range and which isessentially free of hydrogen, is depressured to the desiredaromatization pressure (preferably atmospheric), vaporized, and passedover the ternary molybdenum (IV) oxide on deacidified alumina catalystas described herein. Aromatization is carried out at pressures of about1 to 5 atmospheres, at temperatures in the range of about 900F. to1,050F., and at space velocities of about 0.1 to 4 V/V/Hr. (based onliquid feed volume). The reformate may initially have an octane number(RON) of about to 95, depending on the severity of hydroforming. Thiscan be improved significantly by aromatization according to thisinvention. Enhanced gasoline yields are obtained by combining thearomatization process of this invention with a conventional catalyticreforming or hydroforming process, rather than by use of the catalyticreforming process alone to obtain fuel of the desired octane rating.This is because the catalytic reforming process may be operated undermilder than usual conditions, reducing the amount of hydrocracking withattendant production of light hydrocarbons. The catalysts of the presentinvention are highly selective for the production of aromatics,withlittle hydrocracking taking place. Suppose, for example, that a motorfuel having an RON of 95 is desired. Such a fuel can be produced in acatalytic reformer, but with substantial cracking of paraffins boilingin the motor fuel range. A fuel of the same RON can be produced bycatalytically reforming a feed naphtha to an RON of about 89-9l (sayabout 90), and then aromatizing the reformate to an RON of according tothis invention. Cracking during reforming is much less, giving areformate of considerably greater (typically about 5 to 10% more basedon total reformate) paraffin content. This paraffin content is thenconverted to aromatics at selectivities generally in the range of about85 to 95% according to this invention. This gives greater gasolineyields and smaller amount of C C hydrocarbons which have less value.

The catalyst of this invention can also be used in other hydrogenationand dehydrogenation reactions, for example, dehydrogenation of lowmolecular weight paraffins such as propane and butane, and olefins suchas butenes. It can also be used for other types of reactions, e.g.,hydrodesulfurization of various petroleum fractions, as well ashydrocarbon oxidation.

EXAMPLE 1 A cesium-doped alumina catalyst support was prepared asfollows: 1,560 grams of beta-alumina trihydrate was impregnated with anaqueous solution of 101 grams of CsNO The impregnated alumina was driedand then calcined for 8 hours at 1,600F. The product contained 5 gramatoms of Cs, as C5 0, per 100 moles of A1 with a surface area of about65 to 90 m /g.

A 218 gram portion of the cesium-doped alumina was impregnated with anaqueous solution of 106 grams of ammonium heptamolybdate, (NH Mo O,'4l-l O, dried at 250F., and calcined 4 hours at l,000F. This yieldedmolybdenum trioxide, M00 on cesium-doped alumina containing 30 gramatoms of Mo and gram atoms of Cs per 100 moles of A1 0 A 76 gram portionof molybdenum trioxide on cesium-doped alumina, prepared as describedabove in this Example, was impregnated with an aqueous solution of 38.5grams of Mg(NO '6H O, dried at 250F., and calcined for 4 hours at1,000F. The calcined product, magnesium molybdate, had the compositionof 30 gram atoms of Mg, 30 gram atoms of Mo, and 5 gram atoms of Cs per100 moles of A1 0 The molybdenum in the catalyst was reduced from thehexavalent to the tetravalent state by passing hydrogen through a bed ofcatalyst for 70 minutes at 1,100F., 1 atmosphere, and a space velocityof 100 to 200 V/V/Hr. where the volume of H gas is measured at standardtemperature and pressure.

EXAMPLE 2 Molybdenum trioxide on alumina was prepared as described inExample 1. A 76 gram portion of this product was impregnated with anaqueous solution of 44.6 grams of zinc nitrate, Zn(NO '6H O, dried at212F. to 250F., and calcined for 4 hours at 1,000F. The resulting zincmolybdate on cesium-doped alumina had a composition (expressed in gramatoms per 100 moles of Al O of Zn:Mo:Cs:Al O 30:30:5zl00. The molybdenumin the catalyst was reduced with hydrogen at l,200F., 200 psig, for 1hour.

EXAMPLE 3 Molybdenum trioxide on alumina was prepared as described inExample 1. A 76 gram portion of this product was impregnated with anaqueous solution of 26.9 grams of manganese nitrate, Mn(NO dried at250F., and calcined for 4 hours at l,OOOF. The prod uct had acomposition of 30 gram atoms of Mn, 30 gram atoms of Mo, and 5 gramatoms of Cs, per 100 moles of Al O The molybdenum in the catalyst wasreduced from the hexavalent to the tetravalent state with hydrogen at1,100F., 200 psig, for 1 hour.

EXAMPLE 4 Molybdenum trioxide on alumina was preapred as described inExample 1. A 76 gram portion of this product was impregnated with 29.1grams of cobalt nitrate, Co(NO '6H O, dried at 250F., pelletized intopellets having a diameter of one-sixteenth to one-eighth inch, andcalcined for 4 hours at 1,200F. The product had a composition of gramatoms of Co, gram atoms of Mo, and 5 gram atoms of Cs, per 100 moles A10 This product was reacted with hydrogen at l,l00F. and 200 psig for 1hour to reduce the molybdenum from the hexavalent to the tetravalentstate.

EXAMPLE 5 Molybdenum trioxide on alumina was prepared as described inExample 1. A 76 gram portion of the product was impregnated with 29.1grams of nickel nitrate, Ni(NO '6H 0, dried at 250F., and calcined for 4hours at 1,000F. The product had a composition of 20 gram atoms of Ni,30 gram atoms of Mo, and 5 gram atoms of Cs, per moles A1 0 Themolybdenum was reduced to the tetravalent state with hydrogen at 1,100F.and 200 psig for 1 hour.

Experimental data have clearly demonstrated that the molybdenum anddivalent metals chemically combine to form metallic clusters orcompounds having the formula M Mo O as heretofore described, providedthat a deacidified alumina base is used as a support in formation ofthese catalysts. It is the formation of these compounds which isresponsible for the outstanding and unique catalytic properties.

To demonstrate the necessity of using a deacidified support in formationof the M Mo O cluster compounds, series of data were obtained whereinattempts were made to produce Mg Mo O Zn Mo O and M M0 0 respectively,composited with an alumina support. In one series of runs (D, E and F)magnesium, zinc and nickel catalysts were prepared precisely asdescribed by reference to Examples 1, 2 and 5, respectively, and thecatalysts were reduced, in the final step of catalyst preparation, at1,000F., l,l00F. and l,200F., respectively. In another series of runs(A, B and C) the catalysts were similarly prepared except that thealumina was not deacidified. In other words, but for the presence ofnonsintered, nondeacidified or ordinary alumina vis-a-vis deacidifiedalumina .the conditions employed for the runs were identical. Theresults are given in the following table:

McCarrol et al, JACS, Vol. 79, Page 79, Page 5410 (1957). CDACesiumdoped alumina.

The results thus clearly indicate the presence of the metallic clustersin most of the preparations in which cesium-doped or deacidified aluminais used and conversely the absence of the metallic clusters, as revealedby X-ray analysis, in all preparations in which ordinary A1 0 i.e., notdeacidified or sintened A1 0 is used as the support.

In general, it was also found that increased reduction temperature ledto increased formation of molybdenum metal and decreased clusterformation. The metallic cluster was found for more resistant toreduction than the molybdenum oxide, M00 amounting to a stabilization ofMo (IV) by the divalent cation.

- tions except for a space velocity of 0.45 V/V/Hr. was

carried out using a molybdenum trioxide on cesiumdoped alumina catalystprepared as described in Example I. Results are reported in Table Ibelow.

TABLE 1 S ace Hours Ve ocity, on Selec- Run Catalyst V/V/Hr. StreamConversion tivity 1 Mg molyb- 0.3 59.7 92.2

denum (IV) oxide on 2-2.5 51.1 92.5 Cs-AI O 19-20 30.4 86.7 2 M00 on0.45 0 51.2 85.8

Cs-Al O The responses of the two catalysts to hydrogen regeneration at1,050F., 200 psig, for 2 to 3 hours were significantly different. In thecase of the magnesium molybdenum (ll) oxide, the aromatization increasedto 691 with selectivity of 91.1%, whereas the M00 catalyst gave 35.8%aromatization with 80.0% selectivity.

EXAMPLE 7 This example compares the magnesium molybdenum (IV) oxidecatalyst of Example 1 with chromia on cesium-doped alumina as a catalystfor aromatization of normal heptane. The chromia-on-alumina catalystused for comparison purposes was made by impregnating 214 grams ofcesium-doped alumina, prepared as described in Example 1, with anaqueous solution of 40 grams of CrO (as chromic acid) followed by dryingand then by calcination for 4 hours at 1,000F. Two runs were carriedout, using the magnesium molybdenum (IV) oxide catalyst of Example 1 inRun 1 and the chromia comparison catalyst in Run 2.

Normal heptane was passed through a fixed catalyst bed at atmosphericpressure, a temperature of about 920F. to 925F., and with no hydrogenadded with the feed in each run. Space velocities (based on liquidnhcptane) and results are as indicated in Table 11 below.

TABLE 11 Space Hours Velocity, on 7: Selec- Run Catalyst V/V/Hr. StreamConversion tivity 1 Mg molyb- 0.3 0 65 92 dcnunr (IV) oxide on 2.5 55 93(s-A1 0 on Cs-Al O 62 93 21 18 69 After about 21 hours on stream, eachcatalyst was regenerated by passing hydrogen gas through the catalystbed for about 2.75 to 3 hours at 1,050F. and 200 psig. Aromatization ofn-heptane was again carried out under the same conditions as before,using the regenerated catalysts. After the regenerated catalysts hadbeen on stream about an hour, a 60% conversion with 91% selectivity wasobtained with the catalyst of Example 1, while a 36% conversion withselectivity was obtained with the chromia catalyst.

EXAMPLE 8 Normal heptane vapor was passed through a bed of zincmolybdenum (IV) oxide catalyst prepared as described in Example 2, at atemperature of 920F. to 925F., a presure of 1 atmosphere, and at a spacevelocity of 0.3 V/V/Hr. There was no hydrogen added with the feed. Thecatalyst had been pretreated in a hydrogen atmosphere at 1,200F. and 200psig for 1 hour. The percentage of aromatization and the selectivity asfunctions of time on stream are given in Table III below.

TABLE III Time '72 on Stream Aromatization Selectivity 0 Hrs. 46.7 90.10.75 Hrs. 43.7 92.7 1.75 Hrs. 39.6 91.7 19 Hrs. 15.8 76.5

EXAMPLE 9 Normal heptane vapor free of hydrogen was passed through a bedof manganese molybdenum (1V) oxide catalyst prepared as described inExample 3. The temperature, pressure, and space velocity were 925F., 1atmosphere, and 0.72 V/V/Hr., respectively. The percentage aromatizationwas 22.0%, with 94.5% selectivity.

Earlier, the catalyst in the molybdate (+6) form had been pretreatedwith hydrogen for 1 hour at 575F., then for one-half hour at 750F.,followed by one-half hour at 925F., thcn n-heptane was passed throughthe catalyst at 925F., atmospheric pressure, and at a space velocity of0.3 V/V/Hr. The percentage aromatization was only 2.2%, with aselectivity of 22.5%, indicating that this catalyst reduction procedurewas ineffective.

EXAMPLE 10 gen at 1,100F. and 200 psig for 1 hour. The percentagearomatization was 11.8%, with 81.1% selectivity.

EXAMPLE 1 1 Hydrogen-free normal heptane was passed through a bed ofnickel molybdenum (IV) oxide catalyst prepared as described in Example5, at 920F. to 925F., atmospheric pressure, and a space velocity of 0.72V/V/Hr. The catalyst had been pretreated with hydrogen at 1,100F. and200 psig for 1 hour. The results are given in Table IV below.

An 88 RON reformate from a platinum catalyst reforming (Powerforming)unit, containing 200 ppm of sulfur as thiophene, was passed through abed of supported magnesium molybdenum (IV) oxide catalyst prepared asdescribed in Example 1. This run was carried out at atmosphericpressure, 975F., and a space velocity of 0.75 V/V/Hr., with no hydrogenadded with the feed. The run was carried out for hours, the catalystregenerated with hydrogen, and the run continued for an additional time.Product samples were collected in 2 cuts;.namely, from 3 to 18 hours onstream, and from 18 to 20 hours on stream, and their RON valuesdetermined. After 20 hours, the catalyst was regenerated with hydrogenat 1,050F., 200 psig, for 2% hours. The reformate was then passedthrough the catalyst bed under the same conditions as before. Theresults are shown in Table V below.

Having described the invention, what is claimed is:

1. A process for aromatizing a paraffinic hydrocarbon containing atleast 6 carbon atoms which comprises contacting a feedstock containingsaid hydrocarbon at aromatization conditions with a catalyst comprising(a) a catalytically active material comprising a compound having theformula M MO O where M is a divalent metal having an ionic radius notgreater than 0.95 A, and (b) a support comprising deacidified alumina inwhich said deacidified alumina comprises alumina and a minor amount of ametal oxide selected from the group consisting of Group l-A metal oxidesand Group ll-A metal oxides.

2. A process according to claim 1 in which said feedstock is in thevapor phase.

3. A process according to claim 1 in which said divalent metal isselected from the group consisting of magnesium, zinc, iron, cobalt, andnickel.

4. A process according to claim 1 in which the pressure is in the rangeof about 1 to about 5 atmospheres.

5. A process according to claim 1 in which the reaction temperature isin the range of about 850F. to about 1,050F.

6. A process according to claim 1 in which said feedstock containssubstantially no added hydrogen.

7. A process according to claim 1 in which said support comprisesalumina and a minor amount of a Group l-A metal oxide.

8. A process according to claim 7 in which said Group l-A metal oxide iscesium oxide.

9. A process for upgrading a naphtha boiling in the motor fuel range toincrease the aromatics content and decrease the amount of paraffins,which comprises contacting said naphtha at aromatization conditions witha catalyst comprising (a) a catalytically active material comprising acompound having the formula MzMogog where M is a divalent metal havingan ionic radius not greater than 0.95 A and (b) a support comprisingdeacidified alumina in which said deacidified alumina comprises aluminaand a minor amount of a metal oxide selected from the group consistingof Group I-A metal oxides and Group Il-A metal oxides.

10. A process according to claim 9 in which said naphtha is a reformatefrom a catalytic reforming unit.

11. A process according to claim 10 in which the temperature is in therange of about 850F. to about 1,050F. and the pressure is in the rangeof about 0.5

1. A process for aromatizing a paraffinic hydrocarbon containing atleast 6 carbon atoms which comprises contacting a feedstock containingsaid hydrocarbon at aromatization conditions with a catalyst comprising(a) a catalytically active material comprising a compound having theformula M2Mo3O8 where M is a divalent metal having an ionic radius notgreater than 0.95 A, and (b) a support comprising deacidified alumina inwhich said deacidified alumina comprises alumina and a minor amount of ametal oxide selected from the group consisting of Group I-A metal oxidesand Group II-A metal oxides.
 2. A process according to claim 1 in whichsaid feedstock is in the vapor phase.
 3. A process according to claim 1in which said divalent metal is selected from the group consisting ofmagnesium, zinc, iron, cobalt, and nickel.
 4. A process according toclaim 1 in which the pressure is in the range of about 1 to about 5atmospheres.
 5. A process according to claim 1 in which the reactiontemperature is in the range of about 850*F. to about 1,050*F.
 6. Aprocess according to claim 1 in which said feedstock containssubstantially no added hydrogen.
 7. A process according to claim 1 inwhich said support comprises alumina and a minor amount of a Group I-Ametal oxide.
 8. A process according to claim 7 in which said Group I-Ametal oxide is cesium oxide.
 9. A PROCESS FOR UPGRADING A NAPHTHABOILING IN THE MOTOR FUEL RANGE TO INCREASE THE AROMATICS CONTENT ANDDECREASE THE AMOUNT OF PARAFFINS, WHICH COMPRISES CONTACTING SAIDNAPHTHA AT AROMATIZATION CONDITIONS WITH A CATALYST COMPRISING (A) ACATALYTICALLY ACTIVE MATERIAL COMPRISING A COMPOUND HAVING THE FORMULA10. A process according to claim 9 in which said naphtha is a reformatefrom a catalytic reforming unit.
 11. A process according to claim 10 inwhich the temperature is in the range of about 850*F. to about 1,050*F.and the pressure is in the range of about 0.5 to 5 atmospheres.